Research Information System
Biomass and Bioenergy, vol.212, 2026 (SCI-Expanded, Scopus)
Lignocellulosic biomass biorefining is constantly in need of sustainable and innovative utilization of side streams from processing. Here, the growth of Rhodotorula glutinis yeast and concomitant production of lipids and carotenoids from hemicellulosic hydrolysate (HH) of Salix schwerinii was studied. The effects of pretreatment method, supplemental nutrients, incubation temperature and initial pH on the cell growth, and concentrations of total lipids and carotenoids were investigated in shake flasks. The effect of agitation rate (150, 300 and 600 rpm) as a representative parameter of oxygen transfer efficiency in the medium was examined in a batch bioreactor. The medium pH, yeast cell growth, concentrations of reducing sugars and the components of HH were measured throughout fermentations and the final contents of total lipids, carotenoids and carotenoid fractions were determined. In shake flask experiments, 1 g/L urea and 10 g/L glycerol as supplementation nutrients of HH, 30 °C and pH = 7.0 were determined as the values to be used in bioreactor studies. The HH prepared at 200 °C in a hydrothermal liquification reactor followed by a detoxification procedure was found to be the best substrate. The most produced carotenoid was torularhodin. The highest yeast cell concentration (5.58 g/L), total lipids content (7.7%), total carotenoids content (5.54 mg carotenoids/g DCW) was obtained at 600 rpm. The volumetric mass transfer coefficient kLa showed that high agitation rates increased the mass transfer efficiency providing higher yield of torularhodin (ca.79%). The study showed yeast-facilitated production of a rare carotenoid from side stream of a fast-growing willow species.